Abstract: OBJECTIVE: To observe the damage of target organs of rats exposed to radon，especially the pathological changes of lung tissue，as well as the expressions of RAGE and S100A6 proteins，and to provide information for exploring the mechanisms of potential carcinogenic effects of radon on the lungs. METHODS：16 male rats were randomly divided into 4 groups ，i. e. control group，low (64WLM)、middle (121 WLM) and high (236 WLM) dose groups，with 4 rats in each group. The Wistar rats were exposed to radon in a multifunction ecological radon room at a constant level of 10 0 000 Bq/m3，12 h each day. Pulmonary pathological changes were examined，then the organ coefficients and the rate of bone marrow micronucleus were calculated，8-OHdG in peripheral blood lymphocytes was assessed by ELISA and T-AOC in serum was determined by ultraviolet spectrophotometer. The RAGE and S100A6 proteins were measured by western blot. RESULTS：In the high dose group，inflammatory cell infiltration and thickening of alveolus septa were observed. The liver coefficient increased and the testis coefficient decreased. Rate of bone marrow micronucleus significantly increased. Level of 8-OHdG in peripheral blood lymphocytes was elevated and that of T-AOC declined. The expressions of RAGE and S100A6 in lung tissue were up-regulated in a dose-response relationship. CONCLUSION：Chronic exposure to radon may induce multi-organ damage，especially pathological alterations of lung tissue at high exposure dose.

Key words: radon, RAGE, S100A6, 8-OHdG, T-AOC